The plan of the proposed research is to provide information about basic learning and motivational processes in the early stages of development when aversive controllers of behavior are employed. The specific objective is to assess the effective use of punishment, a powerful determinant of behavioral control, during ontogenesis. The research methodology will use a mammalian animal model (the rat) for ethical considerations, employ the well developed techniques used in animal learning for across-age comparisons, and use stimuli (shock) which equate for motivational factors across ages. Primary questions of interest are whether younger versus older subjects: learn equally well about punishing events; attend to the same environmental contingencies when punished; are sensitive to the same temporal parameters for delivery of punishment; and respond in the same manner when punished. Such information would fulfill the overall objective of providing empirical data on what we might expect organisms of different ages to learn, and how they might demonstrate such learning, through the use of aversive control.